In the past, in a printer for sheet printing and for indicating all sorts of information on print sheets such as a strip-form continuous label and a tag, generally, the print sheet has been wound in a roll, loaded to a sheet supply unit inside the printer, and sent out in a strip form toward the printing unit along a transfer route from this sheet supplying unit.
Particularly, for example, in a case of using a strip-form continuous label, such as a nameplate label, as the print sheet for indicating the item stock number and specific information of various devices, the size of the label pieces (nameplates), a plurality of which are temporarily attached on the strip-form backing sheet, is often comparatively small, compared with other types of labels. Therefore, enabling accurate setting of the relative positions of the transferred continuous label strip (label pieces) with the sheet printing unit is necessary, particularly to ensure print position precision within a predefined range.
In other words, it is necessary to decrease backlash of the rolled print sheet as a rotating body at the sheet supplying unit or unstable rotation by inertia associated with the feeding along the transfer route and intermittent printing actions, thereby providing a predefined tension to the strip-form print sheet to prevent meandering on the transfer route, and also ensuring stability of the transfer to enable accurately obtaining the printing position on the print sheet at the sheet printing unit.
In order to apply the brake (resistance force at the upstream side of the sheet printing unit) and to provide a predefined tension to the rotating body at the sheet supplying unit, a configuration may be used pressing a friction plate with a predefined stress to the flat surface (shaft end surface) located at the side surface of the holding member holding the rotational body. For example, a disk brake may be used.
However, there is a problem that it is not possible to employ the above-mentioned configuration in case there is no flat surface to press the friction plate against on the holding member of the rotating body.
Furthermore, in case the shaft end surface of the holding member of the rotational body has some degree of freedom at the axial direction position, such as in a situation where the widths of the various print sheets are different, etc., there is a problem that it is difficult to apply a constant frictional force on the shaft end surface.
However, as mentioned above, depending on the type of the print sheet loaded at the sheet supplying unit, strict setting of the print position accuracy at the sheet printing unit must be feasible.
Furthermore, as a configuration with the sheet supplying unit provided at a corner portion of the printer is common, the loading operation of the rolled print sheet to the sheet supplying unit is complicated on many occasions. Therefore, there is a demand to simplify the supplying structure and the loading operation of the print sheet to the sheet supplying unit and to ensure the print position accuracy and the transfer stability of the printer.